Largely distribution won't matter, as Python is present and largely self sufficient on virtually all Linux distributions.
If you're wanting to focus on development, I'd recommend Ubuntu. Ubuntu is arguably one of the most fully featured "ready for the user" distributions that makes system administration a snap, so you can focus on the development tasks you want to tackle.
If you have a Linux environment that's a target for your code (like say, RedHat or something), then go with the desktop distribution that matches your target environment (like, say, Fedora for RedHat, Gentoo for Gentoo, Ubuntu for Ubuntu Server, etc.)
Otherwise, all of them are suitable.